Early Luteal Phase Progesterone Kinetics After hCG-Induced Ovulation in Modified Natural Cycle

Inclusion Criteria: * At least 1 follicle of 14 mm or more * Endometrium of 6 mm or more * Plasma luteinizing hormone (LH) less than 2 times basal level (measured at the beginning of the cycle between D1 and D4) and progesteronemia less than 1.5 ng/mL * For whom ovulation induction with recombinant hCG (Ovitrelle) is then proposed (standard care). Exclusion Criteria: * Patient whose venous capital contraindicates repeated blood sampling over a short period of time over a short period. * Patient treated with exogenous natural progesterone (vaginal or injectable) which may interfere or synthetic progesterone, which may interfere with endogenous progesterone secretion. * Patient who has not given written consent to participate in the study. * Patient not fluent in French. * Patient under guardianship, curators or without social security coverage. * Patient participating in another study with an ongoing exclusion period or other interventional research with no ongoing exclusion period involves the use of a drug or procedure capable of altering progesterone levels .